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A COMPARISON  OF  THE  SUGGESTED  METH- 
ODS OF  BACTERIAL  ANALYSIS  USED 
IN  GRADING  MARKET  MILK 


BY 


THEODOR  MARTIN  IIANFT 
AND 

JAMES  ROLLAN  HUDSON 


THESIS 


FOR  THE 

DEGREE  OF  BACHELOR  OF  SCIENCE 

IN 

AGRICULTURE 


COLLEGE  OF  AGRICULTURE 
UNIVERSITY  OF  ILLINOIS 


1922 


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UNIVERSITY  OF  ILLINOIS 


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THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 

.T.hs.P.d.Qr. . I'fe  r t.i.n. . .Ifenf  t„  and_  James  Rc  1 Ian  _ s on 

ENTITLED A.. .C.pi»P:^r.Us.P.n..pf....tLe..  Sugg.es  ted  _ Me  thod^^^  

Ab&  ly.8  iP . . .Va  .P.d . . .In.  .Grading . .f-ferPe  .t . ,M  i Ik 

IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
DEGREE  OF J^S.B0.l9.r...QL..Sci.snR)?...ln...Dai^^^  


HEAD  OF  DEPARTMENT  OF r&ir.y...HuaT:aniry. 


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ACiaiOV/LEDGMSHT . 

The  authors  wish  to  take  this  opportunity  to  express 
theiK  appreciation  for  the  suggestions  and  supervisions  they 
have  received  from  Dr,  M.  J.  Prucha,  Dr.  H.  A.  Ruehe,  Dr. 

P.  W.  Tanner,  and  Mr.  B.  A.  Stiritz. 


» . r 


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Digitized  by  the  Internet  Archive 
in  2015 


i, 


https://archive.org/detaiis/comparisonofsuggOOhanf 


TABLE  OE  COITTEITTS. 

Bac« 

I.  Introduc1;ion._2, 

II.  Object. 2. 

Ill  .Method  of  Procedure. 3. 

A.  Method  of  Sampling. 3. 

B.  Sediment. 3. 

C.  Plate  Method, 3. 

1.  Dilutions. 3. 

2.  Plating. 4. 

3 . Agar . 4. 

4.  Incuhation. 4. 

5.  Counting. 4. 

D.  Erost’s  Microscopic  Plate  Method. 5. 

1.  Preparation  of  Glass  Slides. 5. 

2.  Preparation  of  Plates. 5. 

3.  Incuhation. 5. 

4.  Preparation  of  Plates  for  Counting. 5. 

5.  Counting. 6. 

E.  Breed  Microscopic  Method. 6. 

1.  Preparation  of  Smears. 6. 

2.  Counting. 7. 

E.  Methylene-hlue  Deduction  Test. 7. 

G.  Acidity  Test. 8. 

IV.Experimental . 9. 

Table  I. 10 . 

Table  II  §lass  "A”. 17. 

Table  III  Class  ”A”  . 19. 

Table  IV  Class  ”A"  . 21. 

Table  V Class  ”A"  . 23G 


-L  « 


I.IIITRODUC'TIOII. 

Tliere  is  a grov/ing  tendency  among  milk  dealers  to  purcliase  ; 
milk  on  a grade  "basis,  paying  a "bonus  for  high  grade  milk.  This  [ 

is  an  advisa"ble  practice  in  that  it  tends  to  stimulate  the  pro- 
duction of  better  milk  and  to  enable  the  dealer  to  control  the 
quality  of  his  supply. 

That  the  bacterial  analysis  of  milk  is  of  great  value  in 

1 

the  dairy  industry  has  been  established  beyond  all  doubt.  It  not 
only  gives  some  idea  as  to  the  past  history  of  the  milk  but  also 
as  to  its  future  with  reference  to  keeping  quality,  before  a 
dealer  can  control  the  quality  of  a milk  supply  he  must  Imov/  the 
bacterial  content  of  the  m.ilk  from  each  patron.  It  is  also  valu- 
able to  have  some  loiov/ledge  of  the  sanitary  conditions  under  v/hich 
the  milk  has  been  produced.  This  knov;ledge  can  be  quickly  and 
easily  obtained  by  the  use  of  the  sediment  and  acidity  tests.  The 

sediment  test  shows  the  amount  of  visible  dirt  in  the  m.ilk,  Y/hich 

2 

operates  as  an  incentive  for  the  farmer  to  produce  cleaner  milk. 

The  acidity  test  serves  as  an  index  as  to  the  care  under  which  the 

7 

milk  has  been  produced  and  oi  its  subsequent  handling. 

In  making  the  bacterial  analyses  of  milk,  several  different 
methods  have  been  suggested,  namely:  Standard  Plate  I'ethod,  krost 
"Little"  Plate  liethod,  Sreed  Method,  and  Methylene -blue  Reduction 
Test.  These  methods  were  studied  and  compared  in  this  investigat- 
ion together  vrith  methods  of  analysis  of  keeping  qualities  such  as 
Sediment  and  Acidity  tests. 

This  investigation  was  carried  at  the  University  of  Illinois 
during  the  fall  of  1921  and  the  samples  worked  with  were  taken  from 
the  patrons  of  the  University  creai'iery. 


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II. OBJECT. 

Each  method  of  milli  analysis  that  hears  on  the  bacterial 
content  and  the  heeping  quality  of  milh  has  value  in  a system  of 
grading  milk.  It  was  the  aim  of  the  authors  of  this  study  to 
compare  the  Microscopic  methods  of  Erost  and  Breed  and  the  Methyl- 
ene -blue  Reduction  test  with  the  standard  Elate  method  and  to 
study  the  correlation,  if  any,  between  the  germ  content  of  the 
sample  of  milk  and  its  acidity  and  sediment.  Also  to  study  the 
relation  and  adaptability  of  the  above  tests  in  a system  of  grad- 
ing market  milk. 


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5 


III.  KETHOD  OF  PROCEDimE. 

A.  He  oho d of  sampling. 

100  cc.  of  raw  milk  v;ere  taken  directly  from  the  cans  as  they 
came  into  the  receiving  room,  by  means  of  a sterile  100  cc.  pipet'oe 
and  placed  into  sterile  ground  glass  stoppered  bottles  of  250  cc. 
capacity.  In  most  cases  the  plating  was  done  immediately,  other- 
wise the  samples  were  keep  in  the  ice  chest  until  they  could  be 
plated. 

B.  Sediment. 

Immediately  after  the  sample  for  bacterial  analysis  had  been 
•uaken  the  milk  v;as  thoroughly  stirred  and  one  pint  of  it  taken, 
by  means  of  a dipper,  for  a sediment  test.  I'he  amount  of  sediment 
was  determined  by  means  of  a wizard  sediment  tester,  by  forcing 
the  milk  through  a white  cotton  disc  one  inch  in  diameter  which 
retained  all  the  insoluble  sediment  on  the  disc.  These  discs  were 
mounted  on  cards  as  shov/n  in  Plates  I-IV,  together  with  the  patron 
number  and  the  labors.tory  number  of  the  sample.  The  amount  of  sech 
iment  on  each  disc  was  estimated  comparison  v/ith  a standard 
chart  made  by  v/eighing  accurately  varying  amounts  of  dirt  and  de- 
positing them  on  similar  discs  by  passing  one  pint  of  milk  con- 
taining this  dirt  through  the  discs. 

C.  Plate  Method. 

1.  Dilutions. 

Dilutions  of  1-100  and  1-1000  were  used  in  all  cases  except 
in  a few  instances  where  the  samples  were  Imown  to  be  of  high 
bacterial  content  in  v/hich  case  higher  dilutions  were  employed. 

Dilutions  were  naade  by  adding  one  cc.  of  the  thoroughly  shak- 
en sample  to  99  cc.  of  sterile  v/ater;  of  this  dilution  a one  cc. 
portion  was  added  to  9 cc.  of  sterile  water.  The  dilution  ¥iraters 


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were  sterilized  in  flasks  containing  99cc.  of  distilled  water  and 
in  test  tubes  containing  9 cc.  of  distilled  v/ater  in  the  auto 
clave  at  fifteen  pounds  pressure  for  one  hour.  The  flasks  and  ;; 
tubes  were  stoppered  v/ith  cotton  plug’s  and  a fresh  supply  was  made, 
just  previous  to  each  set  of  saroples  run.  Sterile  straight  sided  : 
pipettes,  graduated  to  deliver  one  cc.  were  used  to  measure  out 
the  portions  of  milk  or  dilution  and  each  pipette  was  used  but 
once  before  it  was  re-sterilized. 

2.  Plating. 

Phe  dilutions  v/ere  plated  in  duplicate  and  for  each  plate 
one  cc.  of  the  dilution  was  measured  into  a petri  dish  by  means 
of  a sterile  one  cc.  pipette.  Then  sufficient  agar  (about  10  cc.) 
was  added  to  cover  the  bottom  of  the  dish.  The  agar  v;as  poured 
at  a temperature  of  45  degrees  U.  so  that  it  would  flow,  and  yet 
not  be  so  hot  as  to  kill  an^^  of  the  organisms.  The  dish  was  moved 
in  a rotary  motion  so  as  to  mix  the  agar  and  sample  thoroughly. 

o . JLgar . 

In  this  work  the  ordinary  nutritive  agar  was  used.  This  med- 
ium was  made  up  as  follows;  10  grams  of  "Difco”  standardized  bactO’ 
peptone  and  5 grams  of  Liebigs  beef  extract  in  one  liter  of  water. 

4.  Incubation. 

The  plates  were  incubated  at  37. 5*^0.  for  forty-eight  hours 
in  a well  ventilated  incubator. 

5.  Counting. 

In  coimting,  those  plates  containing  from  30- to  300  colonies 
Y/ere  selected  and  the  count  multiplied  by  the  dilution  was  report- 
ed as  the  final  count. 

If  there  were  no  plates  v/ithin  these  limits,  the  one  nearest 
to  500  was  counted.  On  miaten  colonies  ir  cxnAnp.  of  3QQ-P..Q.31- 


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plate,  part  of  the  plaice  was  counted  and  the  number  estimated. 
Count inc  v/as  done  with  a lens  and  all  reco{;nizahle  colonies  were 
included,  \7herever  possible  both  plates  of  each  dilution  were 
counted  and  the  avere.ge  reported  as  the  final  count. 

1).  Frost's  Microscopic  Plate  Method. 

1.  Preparation  of  glass  slides. 

The  plates  were  made  on  the  ordinary  microscopic  glass  slides 
(2.5  X 7.5  cm.).  The  slides  v/ere  carefully  cleaned  and  then  ruJ.ecl 
with  a grease  pencil  so  that  a 4 sq.  cm.  area  v/as  inclosed  with  a 
grease  line.  Two  of  these  area  v/ere  marhed  off  on  each  slide  by 
means  of  a cardboard  frame. 

2.  Preparation  of  the  plates. 

The  slides  were  sterilized  by  passing  then  throug'h  a flame 
and  then  0.05(l/20)cc.  of  the  sample  of  mhlh  placed  on  it  with  an 
accurately  calibrated  pipette.  An  equal  amount  of  sterile  nutri- 
ent liquified  agar  at  46°  C.  was  added  and  the  two  drops  thorough- 
ly mixed  by  means  of  a sterile  loop  and  carefully  spread  over  the 
area  marhed  off.  The  agar  was  allowed  to  set  firmly  by  placing 
it  on  a level  surface  under  cover  for  a few  mnnutes.  This  made 
a little  plate  cultured  containing  0.05  cc.  of  milk.  Samples 
were  plated  in  duplicate. 

3.  Incubation. 

Incubation  v/as  accomplished  by  placing  the  little  plates  in 
an  incubator  with  a layer  of  v/ater  in  the  bottom  to  maintain  a 
saturated  atmosphere.  They  v/ere  held  at  37.5°  0.  for  eight  hours. 

4.  Preparation  of  plates  for  counting. 

After  eight  hours  of  incubation  the  plates  were  carefully 
dried,  fixed  by  passing  through  a flame  and  treated  in  a lOp  sol- 
ution of  acetic  acid.  Upon  drying,  the  plates  v/ere  stained  in  a 


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LoeJflers  Methylene -blue  solution  (1-4-J  for  a few  minutes,  and 
decolorized  in  a 95';i  alcoholic  solution,  until  the  hacVgrounds 
were  a pale  blue  and  the  colonies  stood  out  prominently. 

5.  Counting. 

I?or  the  purpose  of  counting  the  colonies,  the  slides  v;ere 
exam.ined  under  the  microscope  with  the  low  pov/er  dry  lens.  This 
revealed  colonies  of  considerable  size  stained  a dark  blue  in  a 
light  blue  field. 

fhe  microscope  was  standardized  by  means  of  a stage  micro- 
meter and  so  adjusted  that  each  microscopic  field  covered  an  area 
of  1/500  sq.  cm..  This  gave  a microscopic  factor  of  4000,  that 
is:  the  average  count  per  field  was  multiplied  by  4000  to  give 
the  final  count.  This  is  true  because  there  v^ere  200  microscopic 
fields  in  each  4 sq.  cm.  area  or  the  area  covered  by  the  plate. 
Each  plate  contained  0.05  cc.  of  milk;  therefore,  each  field  con- 
tained 1/4000  cc.  of  milk. 

Duplicate  plates  were  made  of  each  sample  and  ten  fields  of 
each  plate  counted  and  the  average  taken  for  the  final  count. 

E.  Breed  Microscopic  Method. 

1.  Preparation  of  Smears. 

l/lOO  cc.  of  the  sai^ple  of  milk  was  deposited  upon  a glass 
slide  by  means  of  an  accurately  graduated  pipette.  By  the  use  of 
a sterile  platinum  needle  this  drop  of  milk  was  spread  over  an 
area  of  1 sq.  cm..  This  v/as  accomplished  by  placing  the  slide  on 
a glass  coimting  plate  which  was  ruled  into  one  sq.  cm.  areas. 

After  uniformily  spreading,  the  preparation  was  dried  in  a w 
v;arm  place  upon  a level  surface.  After  dryin^  the  slides  v/ere 
dipped  in  Xylol  for  one  minute,  then  drained  and  the  slides  dried. 
They  were  then  immersed  in  90^^  alcohol  and  then  transferred  to  a 


Ir  , 


- ■ » 


, le/; 


r vr.j^T 


t I , ~. 


•} 


.'J 


■•  J < 


'■  • h ,. . . ■'•'ii:  - £ 

' ' t V ■ ■ -■ 

♦ . ' » * 


.r 


_Ar 


■ ' • « I . U, 

•'>5-  I «, 


i t 


i- 


'k*  ^ ■■ 

"ij-:  •*  ic.h  ’ : U' • r)ji'.:Si  ip.'.,. 


^ at'K"  < 

:--.>V  7 


i t) 


^ m 


U 


f l .•*  * c ■ ,ii6  iHMtIEVrt  :% 

. ' i-  ' t^'" 

'v>  X tt  V-  ..'■''i,':^iE'  ’ ' ff 

• ,A_.  tr 


^ ’*1 1 . ', 


>*,.•:.  •*'  • ' .;  .'.‘.N,  - V-  O 


WT-.„  V > 


‘ ' ' '■  . 4 ■ ' ■•* 


if': 


■ , ■ v.:",,  '.m' 

» ■ v;fi  \^t'  ''/Vi';-  •■«  - «t 

. " ■ ■ ' 7'i"'  ■ • 1 , y 


V '.  , ,i  „..  , It  ¥»./., 

» , / - . . .»  -*< . ’'"^ 


V'7-'- 


■i'-  'f' 


' '^t  ' , ' nv  ’•-  •:: 

;.  7 , : f *5^, 


• f 


,fK-;  ' ^''  ■ T''  ■. 

•■<:,  •i>m.r-  ♦■  ■ .•SI." 


7 


fresh  aqueous  solution  of  Ilethyleno-hlue , The  slides  remained  in 
this  solution  from  5 seconds  to  1 minute,  or  longer,  depending 
upon  the  effect  desired.  They  were  then  rinsed  in  v;ater  to  re- 
move the  surplus  stain,  and  decolorize  in  alcohol,  dried  and  * 

counted. 

2.  Counting. 

For  the  purpose  of  counting'  tho  slides  v/ere  examined  under 
the  microscope  with  the  high  pov/er  oil  immersion  lens.  This  re- 
vealed the  individual  and  clusters  of  "bacteria  stained  a dark  "blue 
in  a light  "blue  field. 

The  microscope  was  standardized  oy  means  of  a stage  micro- 
meter and  so  adjusted  that  each  microscopic  field  covered  an  area 
of  1/3700  sq.  cm...  This  gave  a microscopic  factor  of  370,000; 
that  is;  the  average  count  per  field  was  multiplied  hy  370,000  to 
give  the  final  count.  This  was  due  to  the  fact  that  there  were 
3700  raicrscopic  fields  per  sq.  cm.,  1/100  cc.  of  milk  was  spread 
over  1 sq.  cm. , therefore  each  microscopic  field  contained  1 
1/370,000  cc.  of  milk. 

Duplicate  smears  \7ere  made  of  each  sample  of  milk  and  16 
fields  of  each  smear  v/ere  counted  and  their  average  taken  for  the 
final  count.  Oonnts  of  "both  the  clusters  of  one  or  more  bacteria 
and  individual  bacteria  v;ere  made  and  recorded  separately,  v/here 
the  clusters  consisted  of  large  numbers  of  individuals  an  esti- 
mate was  made. 

D.  liethylene-blue  reduction  Test. 

A 10  cc.  sample  of  the  milk  was  placed  into  a sterile  test 
tube  by  means  of  a sterile  10  cc.  pipette.  To  this  v/as  added  0.5 
cc.  of  liethylene-blue  solution  of  such  strenght  that  one  part  of 


■ 'i^Mll(|LS4^ .» : ■-  ..  -rn*;  *-'  ■.' 4ti<.  - ra^.nc:ir ■ '• ;:.’ raC-t ■ ■; 


V‘  ‘ 


y^f  ir  • ■•  ■I 


a;  A>Jl^ 


*■*•  r ‘ 


In'  ' 

« ..^jr  f|  . 

■ '■  -G. ^ 


I 'fii 


« • .« • 


u .-  ip 


jC 


% .r'v'  '*'  ^'r  ’^4 

• 'L  *4^  - 


^k-  i’ 

r.->i  Jfei.'-  - 


•si'*! 


.1,.  * 


'.l<' 


' ■ ■ ■ ..»  ' f 

:.htd  XKi  ■ 4 |ir :■< J >-, 


•.  ..  /?  t 


: -,.  • /*  ' ^'1 


< ' ^1  - ' ^ 'F  '*  "^' 


,■.  '■  • ' .-.  . ;Tj  ‘-ifc: 


7^'  '■ 


w 


V * 


• ' ' . / 


, 'fr'tf'.jkiv  '"'i 


J I 


•.  f /> 


, r'  T.^  .f 

♦ w I v-ri. 


.i  - - .-r  ^;.pf  . .'p '<J> ' ' ’ir”;'  • - 

k^Mriiwkl  i . . ."  . . ■ tA..  .^  - _ - , - . HiriMi  -KMfUAiii  irM(nnr|-i  > A . - “'* a»  rn  iCmOb  «i  i>ri  AiWmtfcAKi— 


'"■*  '"  "TtS 

^'  ' -Jg  . - 


7i>l  ' 


fi,; 


K 


^ Ot 


,1 

■.» 


8 

the  dry  d^/e  \7as  contained  to  every  200, OCO  parts  of  inilk  "by  v;eiglit  , 

This  solution  was  made  up  as  follows:  The  specific  gravity  of 
the  milk  was  taken  to  he  1.032;  therefore,  the  ariount  of  nilk  used 
v/as  10.32  grams.  This  would  require  the  solution  of  Llethylene-hlu! 
to  contain  .0000516  grains  of  dry  dye  per  cc.  The  solution  was  mad(| 
up  hy  weighing  out  accurately  .1032  grams  of  Medical  I.Iethylene- 
hlue  dye  on  an  analytic  balance  and  dissolving  it  in  one  liter  of 
distilled  viater.  One  cc.  of  this  solution  contained  .0001052 
grams  of  the  dry  dye  and  .5  cc.  contained  the  required  amount  of 
.0000516  grams  of  dry  dye. 

The  milk  in  the  Methylene -blue  solution  were  thoroughly  mix- 
ed and  the  test  tubes  stoppered  with  sterile  cotton  plugs  and  plae ■ 

ed  in  an  electric  incubator  where  they  v/ere  held  at  a constant 

0 

temperature  of  37.5  G..  The  time  required  to  decolorise  was  note,, 

and  recorded. 

G.  Acidity  Test. 

An  acidity  test  was  rim  on  each  sample  by  the  following  meth- 
od: 17.5cc.  of  the  thoroughly  mixed  sample  of  milk  was  placed  in 
a white  cup  by  means  of  a 17.6  cc.  pipette.  The  pipette  was  rinse;, 
with  distilled  water  and  the  rinsings  placed  in  the  cup.  The  per 
cent  acid  was  determined  by  means  of  a j’arrington' s solution 
which  was  made  up  as  follows:  50  Farrington's  tablets  were  pulver- 
ized in  a mortar  and  dissolved  in  970  cc.  of  distilled  water. 

This  gave  an  alkali  solution  of  such  strenght  that  each  cc.  neu- 
tralized .Ol^'o  acid  in  17.5  cc.  of  milk.  Indicator  was  contained 
in  the  tablets.  The  alkali  solution  was  added  drop  by  drop  from 
a 50  cc . burette  mitil  a faint  pink  color  appeared  and  remained 
for  30  seconds.  The  per  cent  acid  v;as  read  directly  from  the  bu- 
retteby  the  number  of  cc.  of  alkali  solution  required. 


-p.rl 


'■  ^ 'U  '■  ’T'S  1tl*t-w:  1 i -”T  ' < 


•^yjatariBs. -I 


' r T 


;T 

1 1 tW^-  • 

1 

V 5-7' 

.r  0 

• "'ii- 

, . J 

O'  V jv; 

J/'V.' 

t “ -1  r^'  ■ 

* , .v/i'. 


. ♦ 


. ,r.  ^ns  .V  ■ ' 


.'  J.  • - If  r'^^»  1 , . ff  ’ iv  ^ >:/ r ' 


J .’  ' ii-3*.9^^C.-\i'  ' 0\I~V  ' * JSIK".  •'•  '.irf  Ji',.  V5i  -^C**' 


.-fe 


*i*-'  ',**f  ‘X  J ( ; _-;.  D^r  f J'.^'  _ 


/.I  -.¥58  .^VJ 


-•(: 


/t'ft 


f *4*'**'^  ’jJL  • 


{,  ' * ./  i\' JC,  y’-'’^',  ^ : 

, . i*  ' ',i;>  * .'>, 

.i  V-j  "vQ.;oJ1 


73 


■•V, , :■  ‘.-,  y ••^.  . V r-^ . a . it-r;^'"  ' I 

, .■■■  ■'  ’ " ■ ■■'■ 

M V ;}  ■ . Mj  A.  \T  TO  ;■  5^: ■5SL-3iri&» ,; : . 

■ • ‘ ■ • • ■¥  \ .,  \S.  ^i.-*  • . ■•  J-  r>*.'  • (.  .UdM  f,,' 


I >.■ 

I 


- 'k. 


*f  ' At  t 


ai' 


:o ..  , o'’ . ^ 


»• , 


LrJ,:^ 


i*’"  ■; 


■¥ 


• H.:; 


’..0..  •.''  S u V -;kL::ir.:<-'.-  .^\a■^.-  iJJi.  ' 

' ■’  V^‘"  ■■  , o3<-^y  ’^'’ 

, '!;.i /jL vov  ‘ vl  a-i', 


• -Tl^-*’  -1  .'L  ^ * , • 

# • • . - , 


MV* 

4’ 


,'  V :l:tixh-  ..  "■•will 


Mj''!  1^ 


t’  , 


lY.  HJSPERHi'LElTTAI. . 

The  Experimental  data  of  this  investigation  is  presented 
in  tabular  form  on  the  follov/ing  pages. 


TABLE  I Corcplete  data  in  Chronological  Order 


o 

[-f-1 

m 

o 

ITV 

o 

irv 

o 

iTV 

vX) 

CM 

CM 

2 

o 

o 

I — 

r— 

VD 

IfV 

CO 

r— 

VO 

f — 

irv 

CO 

-H 

r-t 

rH 

rH 

rH 

rH 

rH 

rH 

rH 

rH 

t—i 

rH 

rH 

r*i 

rH 

O 

• 

-4J 

D 

o 

o 

U'V 

irv 

u^ 

o 

IT\ 

o 

o 

IfV 

o 

O 

o 

o 

# 

• 

• 

• 

• 

# 

• 

• 

• 

• 

• 

# 

• 

• 

rd 

V.O 

-d" 

C<^ 

r- 

CM 

irv 

VO 

CO 

t4-V 

-d- 

d" 

KV 

o> 

CO 

Redaction 

Tinr.e 

i? 

1 

O 

O 

9 

O 

1 — i 
1 

irv 

irv 

'T 

o 

irv 

rH 

1 

uv 

f-C 

1 

VO 

2 

O 

O 

CO 

7-10 

8 

1 

o 

o 

I 

irv 

J- 

irv 

CM 

cIj 

s 

1 

d 

4^ 

c 

>s 

> 

> 

o 

o 

d 

o 

o 

o 

o 

o 

o 

o 

8 

CM 

o 

O 

o 

d 

d 

o 

-d- 

2 

0) 

o 

CO 

o 

CO 

o 

o 

o 

o 

o 

CO 

8 

o 

CO 

o 

o 

«» 

m 

«» 

•• 

«• 

«» 

-d- 

CO 

o 

o 

CM 

o 

rH 

'iR 

CM 

<n 

o 

rH 

o 

CVJ 

#H 

CO 

-d" 

o 

VO 

rH 

o 

o 

EH 

CM 

CM 

rH 

E-t 

f*4 

rH 

O 

o 

O 

o 

o 

o 

O 

o 

8 

O 

8 

O 

o 

O 

o 

o 

o 

o 

o 

O 

crv 

O 

VD 

IfV 

CTV 

rH 

CO 

o 

(TV 

1 

1 

<D  *H 

•» 

«• 

o > 

o 

KV 

j 

_d- 

iH 

CM 

VD 

VO 

cT 

CM 

1 

» 

(M 

1 

CM 

VO 

rH 

CO 

crv 

1^ 

KV 

8 

m tj 

K) 

CM 

CM 

IfV 

rH 

ov 

irv 

•• 

m 

** 

M 

rH 

<M 

9. 

iH 

VO 

8 

O 

o 

O 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

9 

o 

KV 

o 

o\ 

VO 

VD 

o 

KV 

'd  o 

m 

«k 

«» 

•» 

•* 

•« 

«» 

•k 

0) 

CVJ 

CM 

1 

o 

CM 

VD 

r— 

-d" 

to 

LTV 

CO 

irv 

1 

1 

o CO 

rH 

» 

rH 

r-H 

r<^ 

-d- 

CM 

ov 

irv 

irv 

1 

1 

>4  d 

CM 

iH 

IfV 

CM 

rH 

• 

o 

o^ 

CVl 

rH 

-4-* 

d 

8 

o 

o 

8 

8 

O 

8 

O 

8 

8 

g 

o 

o 

g 

o 

o 

8 

8 

8 

y 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

o 

<» 

m 

•» 

m 

•» 

«• 

•* 

•* 

o 

CVJ 

CO 

o 

O 

o 

1 — 

o 

irv 

o 

irv 

iTv 

o 

o 

iH 

rH 

o 

U"V 

VO 

t^v 

o 

iH 

o 

irv 

I — 

o 

to 

<D 

o 

rH 

VO 

J- 

ov 

CTV 

VD 

+> 

•■* 

d 

VX) 

crv 

rH 

rH 

rH 

PL4 

(4 

• <1> 

1 — 

CO 

o^ 

o 

rH 

CM 

KV 

irv 

r— 

05  a 

rH 

rH 

pH 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

0> 

rH  ^ 

i 1 

CO  0 

1 — 

irv 

CM 

rH 

CM 

VD 

irv 

CM 

CO 

r^ 

CO 

CM 

S' 

iH 

'8 

d 

CM 

S' 

rH 

iH 

rH 

rH 

rH 

rH 

rH 

rH 

rH 

rH 

rH 

•H 

iH 

rH 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

<D 

1 

t 

1 

1 

1 

t 

1 

1 

1 

1 

1 

I 

1 

1 

4^ 

CO 

CO 

(TV 

CTv 

Ov 

av 

-d" 

-d 

d 

OJ 

irv 

irv 

irv 

irv 

o{ 

r-C 

r-i 

rH 

rH 

rH 

rH 

CM 

CM 

CM 

CM 

CM 

CM 

CM 

n 

« 

1 

1 

1 

1 

1 

1 

) 

1 

1 

1 

1 

1 

1 

O 

o 

o 

o 

o 

o 

o 

O 

O 

o 

o 

c 

o 

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iH 

rH 

rH 

rH 

rH 

rH 

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I 


' I 

till  I 


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j>  t ‘ I 

) ■ t < t 

n««!adil*a  . ' 


I t t t , 

/ . r.  , I . , 

I . , ■ V 

» » ' I > 


^ i 


1 


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>■  i 

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• *.• 


> ■• 


. ^ ^ c. 


/*7  • ■ ^ •«’ 


/ri  ' 

.'  *'l  ,'  ►* 


',  ' n. 


, ’I  ■ , i > 


I t 


3 

1 


{ I 


< »•  I y M 


X 1 

' t 


■"  ■’  T>  \\ 

■‘•r: 


.‘i'K 

A,  ti\  V'  1 i>; - 


TV.*:  nJiMfSrfKeXttSW^^ 


W V ' 


ll' } I ii 


I 


|| 


TABLE  I (Cont*d) 


» 

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r~- 

CM 

to 

CM 

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60 

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a 

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• 

• 

« 

• 

• 

• 

• 

• 

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# 

• 

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t: 

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CM 

CM 

lOr 

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c 

o 

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£ 

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LTV 

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8 

8 

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lO 

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9 

35 

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1 

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9 

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c:> 

rH 

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rH 

1 — 

LTV 

CM 

rH 

O'N 

© 

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VJD 

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LC\ 

o 

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a 

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8 

o 

60 

rH 

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60 

o 

m 

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8 

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to 

r— 

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o 

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r- 

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© 

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r— 

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O 

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lO 

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m 

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m 

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cr\ 

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CTv 

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60 

to 

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VD 

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(TV 

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4 1 I I 

‘ t ■ I 

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TABLE  II  CLASS  "A" 

Comparison  of  Standard  Plate  Counts 

17  ’ 

to  Frost  Counts. 

ITo. 

Plate  Count 

Frost  Count 

ITo. 

Plate  Count 

Frost  Count  ' 

18 

18,000 

14,400 

47 

39,000 

17,600 

19 

100,000 

8,400 

48 

100,000 

34,000 

21 

60,000 

24,800 

49 

47,750 

31 , 200 

22 

37,000 

14,800 

50 

18,000 

19,200 

23 

400,000 

280,000 

51 

23,000 

28,400 

24 

15,000 

22,000 

52 

31,500 

27,200 

25 

40,000 

100,800 

53 

40,375 

32 , 800 

27 

55,000 

258,400 

54 

23,750 

18,400 

28 

75,000 

17,200 

55 

25,800 

40 , 800 

31 

261,000 

16,000 

56 

28,600 

19,200 

33 

100,000 

60,800 

57 

30,750 

22,000 

34 

70,000 

29,200 

58 

26,100 

28,000 

35 

51,000 

129,600 

59 

19,700 

34,400 

36 

60,000 

30,400 

60 

6,250 

7,600 

38 

92 ,000 

149,600 

61 

11,900 

16,400 

39 

182,000 

148,700 

62 

8,800 

13,200 

40 

26,000 

49 , 200 

63 

19,050 

20,800 

41 

10,000 

4,800 

64 

4,950 

14,800 

42 

70,000 

569,930 

65 

203,500 

490,710 

43 

15,000 

18,800 

66 

9,450 

10,800 

44 

136,000 

27,600 

68 

4,500 

35 , 600 

Clas 

s ”A"  includes  all  milk  v/itk  a PI 

ate  Count  of 

less  than 

500, 

000  per  cc. 

V .. 


7 


\ 


? 


I 


f 


TiiSIiE  II  (Conf 

d) 

18  ' 

ITo. 

Plate  Comit 

Frost  Count 

llo. 

Plate  Count 

Frost  Count 

69 

8,500 

28,800 

91 

4,550 

7,200 

70 

98,500 

184,800 

92 

8,500 

42,800 

71 

241,000 

200,745 

93 

5,900 

6,200 

72 

136,000 

132,000 

94 

22,400 

20,400 

74 

14,000 

34,000 

95 

6,800 

6,200 

75 

60,000 

38,400 

97 

64,700 

109,200 

76 

325,000 

67,600 

99 

306,000 

288,000 

77 

387,000 

1,268,820 

100 

228,000 

29,200 

78 

28,500 

24,400 

101 

117,000 

78,000 

79 

11,400 

10,000 

102 

6,700 

123,200 

80 

142,000 

L, 427, 520 

103 

34,000 

30,400 

81 

1,900 

46 , 400 

104 

20,000 

70,000 

82 

12,000 

27,600 

105 

264,000 

83,600 

83 

12,750 

31,200 

106 

123,000 

40,600 

84 

14,250 

32,000 

107 

85,000 

68,400 

85 

22,450 

42,000 

108 

392,000 

90,400 

86 

108,000 

97,200 

109 

123,000 

194,400 

87 

29,900 

216,000 

110 

4,600 

4-4,000 

88 

28,200 

92,000 

111 

17,000 

163,200 

89 

18,300 

44,400 

113 

188,000 

84,400 

90 

11,800 

12,200 

114 

426,000 

-- 

115 

231,000 

105,600 

. ; — tit..- 


t 


r * 


f 


/ 


.49. ; 


Ti\3LS  III  CLASS  ”A” 
Comparison  of  Standard  Plate 

Counts  to  Breed  Clusi 

19 

er  Counts’. 

llo. 

Plate  Count 

Breed  Cluste 

r 

ITo. 

Plate  Count 

Breed  Cluster  - 

18 

18,000 

12,300 

47 

39,000 

24,600 

19 

100,000 

— 

48 

100,000 

24,600 

21 

60,000 

12,300 

49 

47,750 

— 

22 

37,000 

36,900 

50 

18,000 

— 

23 

400,000 

147,600 

51 

23,000 

12,300 

24 

15,000 

24,600 

52 

31,500 

— 

: 25 

40,000 

98,400 

53 

40,375 

12,300 

27 

55,000 

258,300 

54 

23,750 

— 

28 

75,000 

135,300 

55 

45,800  . 

— 

31 

261,000 

— 

56 

28,600 

24,600 

33 

100,000 

12,300 

57 

30,750 

12,300 

34 

70,000 

61 , 500 

58 

26,100 

— 

35 

51,000 

— 

'59 

19,700 

12,300 

36 

60,000 

-- 

60 

6,250 

-- 

38 

92,000 

49,200 

61 

11,900 

-- 

39 

182,000 

12,300 

62 

8,800 

-- 

40 

26,000 

-- 

63 

19,050 

-- 

41 

10,000 

12,300 

64 

4,950 

__ 

42 

70,000 

24,600 

65 

203,500 

24,600 

43 

15,000 

12,300 

66 

9,450 

12,300 

44 

136,000 

36,900 

68 

4,500 

— 

Class 

"A”  includes  all  milk  with  a Plate  Count  of  less  than 

500,000  per  cc. 

If 


im 


y-i. 


T*) 


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i 


f 


V 


f 


t 


1 


I 


1 


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i 


u .,  : 

t 


4 


TABLE 

III  Cont'd) 

20  ' 

ITo. 

?late  Count  I 

ireed  Cluste] 

» 

ITo. 

Plate  Coujit 

Breed  Cluster 

69 

8,500 

— 

91 

4,550 

— 

70 

98,500 

24,600 

92 

8,500 

12,300 

71 

241,000 

36,900 

93 

5,900 

-- 

72 

136,000 

49,200 

94 

22,400 

49,200 

74 

14,000 

24,600 

95 

6,800 

-- 

75 

60,000 

12,300 

97 

64,700 

270,000 

76 

325,000 

56,900 

99 

306,000 

430,500 

77 

587,000 

282,900 

100 

228,000 

24,600 

78 

23,500 

-- 

101 

117,000 

Too  heavy 

79 

11,400 

— 

102 

6,700 

73,000 

80 

142,000 

356,700 

103 

34,000 

12,300 

81 

1,900 

12,300 

104 

20,000 

12,300 

82 

12,000 

12,300 

105 

264,000 

787,200 

83 

12,000 

— 

106 

123,000 

12,300 

84 

14,250 

12,300 

107 

85,000 

147,600 

85 

22,450 

12,300 

108 

392,000 

479,700 

86 

108,000 

12,300 

109 

123,000 

47,970 

87 

29,900 

12,300 

110 

4,600 

-- 

88 

28,200 

12,300 

111 

17,000 

541,200 

89 

18,300 

12,300 

115 

188,000 

147,600 

90 

11,800 

— 

114 

426,000 

Too  heavy 

115 

231,000 

49,200 

v*?i 
. * 1 


f 


fl 


9 


9 


e 


t 


7 


? 


/ 

> 


I 


f 


( 


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t 


9 


i 


5 


. : r . . . rjT 


T 


I 


i 


t 


9 


f 


■V  r,'v 


f . 

k« 


•*  ■ 


V 


TABLE 

IV  CLASS  " 

A” 

21 

Comparison  of  Standard  Plate  Counts  to 

the  Breed  Individual  Counts 

ITo. 

Plate  Count 

Breed  Ind. 

Bo. 

Plate  Count 

Breed  Ind. 

18 

18,000 

223,900 

47 

39,000 

98,400 

19 

100,000 

— 

48 

100,000 

36,900 

21 

60,000 

24,600 

49 

47,750 

-- 

22 

37,000 

61,500 

50 

18,000 

— 

23 

400,000 

1,512,900 

51 

23,000 

24,600 

24 

15,000 

86,100 

52 

31,500 

— 

25 

40,000 

196,800 

53 

40,375 

36,900 

27 

55,000 

7,537,400 

54 

23,750 

-- 

28 

75,000 

282,900 

55 

45,800 

— 

31 

261,000 

— 

56 

28,600 

49,200 

33 

100,000 

24,600 

57 

30,750 

36,900 

34 

70,000 

209,100 

58 

26,100 

— 

35 

51,000 

— 

59 

19,700 

24,600 

36 

60,000 

— 

60 

6,250 

— 

38 

92,000 

123,000 

61 

11,900 

— 

39 

182,000 

123,000 

62 

8,800 

-- 

40 

26,000 

— 

63 

19,050 

— 

41 

10,000 

98,400 

64 

4,950 

-- 

42 

70,000 

282,900 

65 

203,500 

86,100 

43 

15,000 

49,200 

66 

9,450 

49,200 

44 

136,000 

86,100 

68 

4,600 

— 

Clas 

50C, 

s "A"  includes  all  milk  v;ith  a Plate  Count  of 
000  per  cc. 

less  than 

f 


x-^ 

'U- 


f 


5"<-asgs 


TABLS 

IV  (Cont’d) 

22  ' 

ITo. 

Plate  Coimt 

Breed  Ind. 

ITo. 

Plate  Count 

Breed  Ind. 

69 

8,500 

— 

91  ■ 

4 , L'L»0 

70 

98,500 

61,500 

92 

8,500 

61,500 

71 

241,000 

73,800 

93 

5,900 

-- 

72 

136,000 

135,300 

94 

22,400 

693,600 

74 

14,000 

61,500 

95 

6,800 

-- 

75 

60,000 

12,000 

96 

64,700 

666,000 

76 

326,000 

73,800 

99 

306,000 

1,940,700 

77 

387,000 

750,300 

100 

228,000 

196,800 

78 

23,500 

-- 

101 

117,000 

Too  heavy 

79 

11,400 

-- 

102 

6,700 

430,500 

80 

142,000 

3,161,100 

103 

34,000 

24,600 

81 

1,900 

24,600 

104 

20,000 

61,500 

82 

12,000 

615,000 

105 

264,000 

3,271,800 

83 

12,750 

-- 

106 

123,000 

369,000 

84 

14,250 

24,600 

107 

85,000 

1,279,200 

85 

22,450 

49,200 

108 

592,000 

3,370,200 

86 

108,000 

615,000 

109 

123,000 

600,240 

87 

29,900 

1,230,000 

110 

4,600 

— 

88 

28,200 

49,200 

111 

17,000 

1,303,800 

89 

18,300 

49,200 

113 

188,000 

528,900 

90 

11,800 

-- 

114 

426,000 

Too  heavy 

115 

231,000 

172,000 

-V 


if 


I 

5 . . . 1 


25 


TABLE  V CLASS  "A” 

Conparison  of  Standard  Plate  Counts  to  the  hethylene  Blue 
Reduetion  Tests. 

Time  Recorded  in  Hours  and  Minutes. 


Ho. 

Plate  Count 

Reduction 

Ho. 

Plate  Count 

Reduction 

18 

18,000 

6-00 

47 

39,000 

8-45 

19 

100,000 

5-10 

48 

100,000 

8-40 

21 

60,000 

4-15 

49 

47,750 

9-00 

22 

37,000 

6-15 

50 

18,000 

8-45 

23 

400,000 

3-40 

51 

23,000 

9-00 

24 

15,000 

8-00 

52 

31,500 

9-20 

25 

40 , 0.00 

7-10 

53 

40,375 

8-40 

27 

55 ,000 

5-00 

54 

23,750 

9-20 

28 

75,000 

4-30 

55 

45 , 800 

11-15 

31 

261,000 

7-00 

56 

28,600 

11-10 

33 

100,000 

7-30 

57 

35,750 

8-00 

34 

70,000 

7-30 

58 

26,100 

IOtOC 

35 

51,000 

7-00 

59 

19,700 

9-15 

36 

60,000 

7-00 

60 

6,250 

10-15 

38 

92,000 

6-00 

61 

11,900 

10-00 

39 

182,000 

6-15 

62 

8,800 

11-40 

40 

26,000 

6-30 

63 

19,050 

13-25 

41 

10,000 

6-45 

64 

4,950 

12-25 

42 

70,000 

5-00 

65 

203,500 

11-15 

43 

15,000 

8-45 

66 

9,450) 

7-10 

44 

136,000 

7-45 

68 

4,500 

12-00 

Class  "A”  includes  all  milh  v;ith  a Plate  Count  of  less  than 
500,000  per  cc. 


p 


i 


If.  A . Oc'  Ah 


TABLE  V (Cont’d) 

24  ' 

llo; 

Plate  Count 

Reduction 

IIo. 

Plate  Count 

Reduction 

69 

8,500 

11-40 

91 

4,550 

9-40 

70 

98,500 

9-35 

92 

8,500 

8-20 

71 

241,000 

4-40 

93 

5,900 

8-50 

72 

136,000 

4-40 

94 

22,400 

12-00 

74 

14,000 

11-15 

95 

6,800 

12-00 

75 

60,000 

10-45 

97 

64,700 

4-20 

76 

325,000 

5-50 

99 

306,000 

5-20 

77 

387,000 

4-40 

100 

228,000 

12-00 

78 

23,500 

10-30 

101 

117,000 

00-35 

79 

11,400 

10-30 

102 

6,700 

12-00 

80 

142,000 

9-25 

103 

34,000 

9-40 

81 

1,900 

11-05 

104 

20,000 

12-40 

82 

12,000 

10-30 

105 

264,000 

2-20 

83 

12,750 

9-00 

106 

123,000 

5-20 

84 

14,250 

8-20 

107 

85,000 

5-20 

85 

22,450 

8-20 

108 

392,000 

3-10 

86 

108,000 

7-00 

109 

123,000 

5-20 

87 

29,900 

9-00 

110 

4,600 

9-40 

88 

28,200 

8-20 

111 

17,000 

8-20 

89 

18,300 

9-40 

113 

188,000 

5-20 

90 

11,800 

8-20 

114 

426,000 

0-52 

115 

231,000 

8-20 

'i  . 


Si 


>'• 


i,  F 

f ■ \ 


I ' ■ ^ ' i* 


t • 
i 


:.M 


TABLE 

71  CLASS  ”A" 

25  ' 

Comparison  of  Standard  Plate  Counts  to  the  Acidity  Te 

sts. 

Eo. 

Plate  Count 

•H 

O 

ITo. 

Plate  Count 

fo  Acid 

18 

18,000 

.175 

47 

89,000 

.157 

19 

100,000 

.170 

48 

100,000 

.154 

21 

60,000 

.150 

49 

47,750 

.158 

22 

37,000 

.145 

50 

18,000 

.163 

23 

400,000 

.180 

51 

23,000 

.147 

24 

15,000 

.175 

52 

31,500 

.147 

25 

40,000 

.166 

55 

40,375 

.213 

27 

55,000 

.15E 

54 

23,750 

. .162 

28 

75,000 

.148 

55 

45,800 

.164 

31 

261,000 

.154 

56 

28,600 

.188 

33 

100,000 

.130 

57 

30,750 

.188 

34 

70,000 

.186 

58 

26,100 

.210 

35 

51,000 

.160 

59 

19,700 

.177 

36 

60,000 

.167 

60 

6,250 

.193 

38 

92,000 

.179 

61 

11,900 

.162 

39 

182,000 

.143 

62 

8,800 

.188 

40 

26,000 

.165 

63 

19,050 

.174 

41 

10,000 

.178 

64 

4,950 

.182 

4S 

70,000 

.165 

65 

203,500 

.165 

43 

15,000 

.168 

66 

9,450 

.179 

44 

136,000 

.169 

68 

4,500 

.178 

Class  "A"  includes 
500,000  per  cc. 

all  milk  v/ith  a Plate  Count  of  less  than 

j- 


V ' 


I 


. ■■  ..-J  ,( 


« 


* ^ 


TABLE  VI  (Conf 

d) 

26  !l 

. 1 

♦ 

o 

Plate  Count 

io  Acid 

ITo. 

Plate  Count 

fo  Acid 

69 

8,500 

.211 

91 

4,550 

.195 

70 

98,500 

.162 

92 

8,500 

.175 

71 

241,000 

.152 

93 

5,900 

.182 

7E 

136,000 

.163 

94 

22,400 

.159 

74 

14,000 

.154 

95 

6,800 

.175 

75 

60,000 

.172 

97 

64,700 

.175 

76 

325,000 

.162 

99 

306,000 

.178 

77 

387,000 

.158 

100 

228,000 

.200 

78 

23,500 

.162 

101 

117,000 

.210 

79 

11,400 

.182 

102 

6,700 

.174 

80 

142,000 

.161 

103 

34^,000 

.182 

81 

1,900 

.182 

104 

20,000 

.175 

82 

12,000 

.184 

105 

264,000 

.164 

83 

12,750 

.163 

106 

123,000 

.162 

84 

14,250 

.191 

107 

85,000 

.162 

85 

22,450 

.171 

108 

392,000 

.171 

86 

108,000 

.174 

109 

123,000 

.170 

87 

29,900 

.186 

no 

4,600 

.175 

88 

28,200 

.182 

111 

17,000 

.188 

89 

18,300 

.171 

113 

188,000 

.171 

90 

11,800 

.165 

114 

426,000 

.182 

115 

231,000 

.174 

J*'r9'*Tr;  ‘f* 


t 


t 


e 


^.:7 

TABLE  YII  CLA3;: 

"A" 

Comparison  of  Standard  Plate  Counts  to 

the  Sediment 

Tests. 

Sediment  expressed  in  Mgs.  per 

Pint. 

Ho. 

Plate  Count 

Sediment 

Ho. 

Plate  Count 

Sediment 

18 

18,000 

4.0 

47 

39,000 

1.5 

19 

100,000 

3.5 

48 

100,000 

2.0 

21 

60,000 

2.5 

49 

47,750 

2.0 

22 

37,000 

5.0 

50 

18,000 

2.5 

23 

400,000 

3.5 

51 

23,000 

3.0 

24 

15,000 

6.0 

52 

31,500 

7.5 

25 

40,000 

8.0 

53 

40,375 

30,0 

27 

55,000 

3.0 

54 

23,750 

4.0 

28 

75,000 

4.0 

55 

45,800 

2.0 

31 

261,000 

3.0 

56 

28,600 

2.5 

33 

100,000 

1.0 

57 

30,750 

2.0 

34 

70,000 

1.0 

58 

26,100 

1.0 

35 

51,000 

8.0 

59 

19,700 

5.0 

36 

60,000 

2.0 

60 

6,250 

5.0 

38 

92,000 

7.5 

61 

11,900 

2.0 

39 

182,000 

10.0 

62 

8,800 

2.5 

4o 

26,000 

7.5 

63 

19,050 

2.5 

41 

10,000 

5.0 

64 

4,950 

5.0 

42 

70,000 

1.0 

65 

203,500 

4.5 

43 

15,000 

5.0 

66 

9,450 

5.0 

44 

136,000 

7.5 

68 

4,500 

5.0 

Class  "A"  includes  all  milk  with  a Plate  Count  of  less  than 
500,000  per  cc. 

* ' * . ■ ■ * ~ * 1 - < 1 .1  ■ 1 ..  . ■ -Ml  1 ..  . > 

28  ' 

TABLE  VII  (Conf 

d) 

llo. 

Plate  Count 

Sediment 

llo. 

Plate  Count 

Sediment 

69 

8,500 

5,0 

91 

4, 550 

4.0 

70 

88,500 

3,0 

92 

8,500 

2.0 

71 

241,000 

20.0 

93 

5,900 

2.0 

72 

136,000 

5.0 

94 

22,400 

2.5 

74 

14,000 

8.0 

95 

6,800 

7.0 

75 

60,000 

2.6 

97 

64,700 

6.0 

7b 

325,000 

6.0 

99 

306,000 

4.0 

77 

887,000 

0 

4.0 

100 

228,000 

5.0 

78 

23,500 

6.0 

101 

117,000 

9.0 

79 

11,400 

20,0 

102 

6,700 

7.5 

80 

142,000 

15.0 

103 

34,000 

4.5 

81 

1,900 

7.5 

104 

20,000 

3.5 

82 

12,000 

4.5 

105 

264,000 

5.5 

83 

12,750 

3.5 

106 

123,000 

5.0 

84 

14,250 

4.0 

107 

85,000 

5.0 

85 

22,460 

4.0 

108 

392,000 

15.0 

86 

108,000 

3.5 

109 

123,000 

3.5 

87 

29,900 

4.0 

110 

4,600 

4.0 

88 

28,200 

4.0 

111 

17,000 

5.5 

89 

18,300 

4.0 

113 

188,000 

5.0 

90 

11,800 

4.0 

114 

426,000 

10.0 

115 

231,000 

7.5 

- 


Ho. 

Plate  Coimt 

Erost  Coiuit 

IIo. 

Plate  Count 

Erost  Count 

29 

900,000 

356,800 

67 

995,000 

3,717,500 

30 

680,000 

132,000 

73 

910,000 

942,460 

32 

640,000 

2,862,000 

112 

920,000 

88,800 

46 

672,000 

260,225 

TABLE  VIII  class  "B” 

CoLiparison  of  Standard  Plate  Counts  to  Erost  Counts. 


Class  ”B"  includes  all  milli  with  a Plate  Count  of 
500,000  to  1,000,000  per  cc. 


TABIdil  IZ  OInVSS  "B" 

Comparison  of  Standard  Plate  Co  unis  to  Breed  Cluster  Counts 


ITo. 

Plate  Count; 

3reed  Cluster 

ITo. 

Plate  Count 

Breed  Cluster 

29 

900,000 

67 

995,000 

1,887,000 

30 

680,000 

73 

910,000 

390,400 

32 

640,000 

615,000 

112 

920,000 

221,400 

46 

672,000 

36,900 

Class  ”B"  includes  all  milk  with  a Plate  Count  of 
500,000  to  1,00Q,C00  per  cc. 


TABLE  Z CLASS  "B" 

Comparison  of  Standard  Plate  Counts  to  Breed  Individual  Counts 


ITo. 

Plate  Count 

Breed  Ind. 

ITo. 

Plate  Count 

Breed  Ind. 

29 

900,000 

67 

995,000 

4,566,000 

30 

680,000 

73 

910,000 

2,201,700 

32 

640,000 

1,720,000 

112 

920,000 

1,599,000 

46 

672,000 

98,400 

Ulass  "B"  inciuaes  ai.i  m.iim  *wi 

un  a ruaue  counu  or 

500,000  to  1,000,000  per  cc, 


I 


i » 


• « 


• i 


( 


x*r< 


j*'. 


• *'Vj 


TABLE  XI  CLASS  "B" 

Comparison  of  Standard  Plate  Counts  to 
Reduction  Tests. 

Time  Recorded  in  Hours  and  Llinutes. 

30  ' 

the  llethylene  Blue 

ITo. 

Plate  Count 

Reduction 

ITo. 

Plate  Count 

Reduc  tion 

29 

900,000 

0-25 

67 

995,000 

5-0 

30 

680,000 

4-  0 

73 

910,000 

4-40 

32 

640,000 

7-  0 

112 

920,000 

5-20 

46 

672,000 

4-45 

Class 

"B”  includes  all  milh  v/i’ 

fch  a Plate  Count  of 

500,000  to  1,000,000  per  cc. 

TABLE 

XII  CLASS  "B" 

Comparison  of  Standard  Plate  Counts  to 

Acidity  Tests. 

ITo. 

Plate  Count 

^0  Acid 

ITo. 

Plate  Count 

fo  Acid 

29 

900,000 

.171 

67 

995,000 

.168 

30 

680,000 

.180 

73 

910,000 

.157 

32 

640,000 

.179 

112 

920,000 

.192 

46 

672,000 

.179 

Class 

"B"  includes  all  milli  uith  a Plate  Count  of 

500,000  to  1,000,000  per  cc. 

TABLE 

XEII  CLiiSS 

"B" 

Comparison  of  Standard  Plate  Count  to  the  Sediment 

Tests. 

Sediment  expressed  in  Mgs.  per 

pint. 

ITo. 

Plate  Count 

Sediment 

ITo. 

Plate  Count 

Sediment 

29 

900,000 

4.0 

67 

995,000 

4.0 

30 

680,000 

3.0 

73 

910,000 

5.0 

32 

640,000 

3.5 

112 

920,000 

4.5 

46 

67^,000 

6.5 

Class 

”B”  includes  all  mil  A v/ltli  a Pla'' 

be  Count  of 

500,000  to  1,000,000  per  cc. 

• • 


* f 

1 


J 


f‘  : 


i 'J 


\ 


3 


f 


/•  \ 


f 


9 


:■! 


. • vy  ' « 


A1 


Ho. 

Plate  Counts 

Frost  Count 

Ho. 

Plate  Count 

Frost  Court 

17 

6,012,000 

Too  heavy 

45 

7,100,000 

10,000 

20 

19,650,000 

Too  heavy 

96 

1,150,000 

117,200 

26 

1,100,000 

61,200 

98 

1,094,000 

2,253,250 

37 

2.490.000 

1.858.750 

117 

10.985.000 

230,800 

TABLE  XIV  Class  "C” 

Comparison  of  Standard  Plate  Counts  to  Frost  Counts. 


31 


Class  "C"  includes  all  milk  v/ith  a Plate  Count  of  over 

1,000,000  per  cc. 


TABLE  XV  CLASS  ”C" 

Comparison  of  Standard  Plate  Counts  to  Breed  Cluster  Counts. 


Ho. 


Plate  Count  Breed  Cluster 


ITo.  Plate  Count 


Breed  Cluste]' 


17 

20 

26 

37 


6,012,000 

19 ,650,000 

1.900.000 

2.490.000 


9,472,000 

12,210,000 

550,000 

270,600 


45 

96 

98 

117 


7.100.000 

1.150.000 

1.094.000 

10,985,000 


Too  heavy 
Too  heavy 
1,143,900 
110,700 


Class  "C”  includes  all  milk  with  a Plate  Count  of  over 

1,000,000  per  cc. 


TABLE  XVI  CL/iSS  ”C" 

Comparison  of  Standard  Plate  Counts  to  Breed  Individual  Counts. 


Ho. 


Plate  Count 


Breed  Ind. 


Ho. 


Plate  Count 


Breed  Ind. 


17 

20 

26 

37 


6,012,000 

19,650,000 

1.900.000 

2.490.000 


21.830.000 

30.230.000 

6,970,000 

668,800 


45 

96 

98 

117 


7.100.000 

1.150.000 

1.094.000 

10,985,000 


Too  heavy 
Too  heavy 
3,456,300 
344,400 


Class  "C"  includes  all  milk  with  a Plate  Count  of  over 

1,000,000  per  cc. 


: .V:  , 


1 


r 


r < 


f f 


C 


TABLE  XVII  CLASS  "C" 

Comparison  of  Standard  Plate  Counts  to  Methylene  Blue 
Reduction  Tests. 


32 


Ti  m<^ 

iTo.  : 

?late  Count 

.U  UJ.  U Ctllu.  XdXil 

Reduction 

. u c s • 
ITo. 

Plate  Count 

Reduction 

17 

6,012,000 

0-45 

45 

7,100,000 

O-IO 

20 

19,650,000 

0-45 

96 

1,150,000 

0-35 

26 

1,900,000 

I-  0 

98 

1,094,000 

I-IO 

37 

2,490,000 

10-40 

II7 

10,985,000 

9-50 

({Jlass  "C-'  includes  all  milk  with  a Plate  Count  of  over 
1 , COO , CCC  vor  i^- c . 


TiOBLS  XVIII  CLASS  "C" 

Comparison  of  Standard  Plate  Count  to  the  Acidity  Tests. 


Ho. 

Plate  Count 

fo  Acid 

ITo. 

Plate  Count 

fo  Acid 

17 

6,012,000 

.130 

45 

7,100,000 

.383 

20 

19,650,000 

.165 

96 

1,150,000 

.174 

26 

1,900,000 

.172 

98 

1,094,000 

.181 

37 

2,490,000 

.152 

II7 

16,985,000 

.164 

Class  "C"  includes  all  milk  with  a Plate  Count  of  over 
I ,000,000  per  cc. 


TABLE  XIX  CLASS  "C" 

Comparison  of  Standard  Plate  Counts  to  the  Sediment  Tests 
Sediment  Expressed  in  Mgs.  per  Pint. 


ITo. 

Plate  Count 

Sediment 

Ho. 

Plate  Count 

Sediment 

17 

6,012,000 

6.0 

45 

7,100,000 

7.5 

20 

19,650,000 

7.5 

96 

1,150,000 

5.0 

26 

1,900,000 

7.5 

98 

1,094,000 

3.5 

37 

2,490,000 

3.5 

II7 

10,985,000 

5.0 

Class 

1,000 

"C"  includes 
,000  per  cc. 

all  milk  with  a Plate  Count  of  over 

t ? 


t 


J Jh 


f 


t 


t 


TABLE  XX  CLASS  "A" 

Comparison  of  Breed  Cluster  Counts  to 

33 

the  Breed  Individual  Counts. 

ITo. 

Breed  Cluste 

r Breed  Ind. 

ITo. 

Breed  Clustei 

Breed  Ind, 

18 

12,300 

223,900 

59 

12,300 

24,600 

21 

12,300 

24,600 

65 

24,600 

86,100 

22 

36,900 

61,500 

66 

12,300 

49.200 

23 

147,600 

1,512,900 

70 

24,600 

61,500 

24 

24,600 

86,100 

71 

36,900 

73,800 

25 

98,400 

196,800 

72 

49,200 

135,300 

27 

258,300 

7,537,400 

73 

390,400 

2,201,  700 

28 

135,300 

282,900 

74 

24,600 

61,500 

33 

12,300 

24,600 

75 

12,300 

12,300 

34 

61,500 

209,100 

76 

36,900 

73,800 

37 

270,600 

668,100 

77 

282,900 

750,300 

38 

49,200 

123,000 

80 

356,700 

3,161,100 

39 

12,300 

123,000 

81 

12,300 

24,600 

41 

12,300 

98,400 

82 

12,300 

615,000 

42 

24,600 

182,900 

84 

12,300 

24,600 

43 

12,300 

49,200 

85 

12,300 

49,200 

44 

36,900 

86,100 

86 

12,300 

615,000 

46 

36,900 

98,400 

87 

12,300 

1,230,000 

47 

24,600 

98,400 

88 

12,300 

49,200 

48 

24,600 

36,900 

89 

12,300 

49,200 

51 

12,300 

24,600 

92 

12,300 

61,500 

53 

12,300 

36,900 

94 

49,200 

693,600 

56 

24,600 

49,200 

97 

270,000 

666,000 

57 

12.500 

56.900 

99 

450 .500 

1,09^,700 

Cla£s__"A”  includes  all  milkjzith  a Pinti?  rvf 

than_  JQO  . coo  . 

34 

TABLE  :DC(Cont’d) 

llo. 

Breed  Cluste: 

1*  Breed  Ind. 

IIo. 

Breed  Cluster 

Breed  Ind. 

' 100 
102 

103 

104 
106 
107 

24,600 

73,800 

12,300 

12,300 

12,300 

147,600 

196,800 

430,500 

24,600 

61,500 

369,000 

1,271,200 

108 

109 

112 

113 

115 

117 

479.700 
47,970 

221,400 

147,600 

49,200 

110.700 

3,370,200 

600,240 

1,599,000 

528,900 

172,000 

344,400 

TABLE  XXI  CLASS ”B" 

Comparison  of  the  Breed  Cluster  Counts  to  the  Breed  Ind*  Counts. 

llo. 

Breed  Cluste: 

: Breed  Ind. 

ITo. 

Breed  Clustei 

Breed  Ind. 

26 

52 

555 .000 

615.000 

6.970.000 

1.720.000 

105 

111 

787.200 

541.200 

3,271,800 

1,303,300 

Class  ”B”  includes  all  milk  with  a plate  count  of  500,000  to 
1,000,000  per  cc. 

TABLE  XZlI  CLASS  ”C" 

! Comparison  of  the  Breed  Cluster  Counts  to  the  Breed  Ind.  Counts. 

ITo. 

Breed  Cluste 

c Breed  Ind. 

ITo. 

Breed  Clustes 

Breed  Ind. 

17 

20 

9,472,000 

12,210,000 

21.830.000 

30.230.000 

67 

98 

1,887,000 

1,143,900 

4,366,000 

3,456,300 

Class  ”C"  includes  all  milk  v/it 
1,000,000  per  cc. 

h a plate  count  of  over 

C 


35 

TABLE  XXIII 

Distribution  of  Milk  into  the  three  classes  by  the  various 
methods  used. 


Classes 

Plate 

Erost 

Breed  Cluste 

r Breed  Ind, 

Class  "A" 

85 

82 

83 

67 

Class 

7 

1 

1 

0 

Class  "C" 

8 

4 

5 

6 

Totals 

100 

87 

89 

73 

Classification  was  made  according  to  the  results  obtained  by 
the  Standard  Plate  Method. 


-r  Qjf 


I 


J ■ fr) 

iw  ^ 

«-. 

' i' 

1 


i 


I 


f 


J 


H 


r 


I 


rV 


I 


CHART- 1 


3J?TED  - INO I V 


Breed- CLu^tetr 


7T?06T 


'PlATE 


so  a 000 


\ : I ; i 1 . _1 1 I 1 


/oo  <^0  zo  ^0  so  -fo  so  zo  o 20  so  -jta 

A/ur^&ER  OF  SAtAPLE5 


breed  -Indwidual 


-CLUSTEJ5 


TF05T 


VLATE 

all  others  600,000-/,  000,000 

I . . , I i 1 I ; I 


/eo  OO  3oTv  Topy  ^-o  3o  ao  /o  o -o  ao  so  s<o  6'o  io  70  so  Oo  'oo 

A/0MQE7^  of  6 ample 6 


Breed  -Ia/ dividual 


BTiEED-CLuZTEIS 


TIEOST 


PLATE 


-1,000,000  i-/, 000000 

I ! 1 I I I I I I i I i I I I ( f I I I 


■ 00  sv  go  70  Co  *0  30  so  ‘'o  (2  to  3o  zo  4-0  so  60  70  60  foo 

A/oaabeje  of  •Samples 


PLATE  I Samples  IV -41. 


57 


n 


(,0Mg6 

AciDiTy-./50 


22 


S.O  Mgi 
AaDtTY-l4S 


27 


/5 


ACIDITV-./52 


/6 


28 


40  Mp 

AciDiTy-.l75 


23 


25 


S.SMff. 

Acidity  -.180 


28 


21, 


40AAqi 

I Acidity -./48 


19 


5-5  Mp 
AciDITY-.no 


24 


286 


C O 

Acidity -.ns 


52 


20 


J SMgs. 

Acidity  -.n^ 


57 


n 


L- 


5 S Mgs 

Acidity -.752 


55 


t . 


/ S AAgs 

Acidity -.750 


58 


78 


•V;  ■ 

75  Mgs 
ACIDITV-.779 


29 


24 


4 0/^<js 

Acidity-770 


54 


25 


20 


12  2/ 


TSMgs 
Acidity— .765 


25 


287 


s o M55 
AciDlTV~./i>f> 


2 5 Mgs 
Acidity— ./SO 


25 


/? 


30 


29 


u 


^.0  AAfi. 

Acidity-.780 


55 


52 


, -Ik-V-Vv 


: iV 


/OMgs  SOMgs  20/Y<gs 

Acidity-  786  Acidity -.760  \ Acidity -.767 


7 SMgs. 

AciDITY-.n2 


51 


76 


SSMgs 

ACIDITY-J54 


56 


75 


39  4 \40 

"II 

tO.O 

Acidity-745 


76 


; 4 


\Acidity-/6S 


4! 


28 


S OAy\^S 

Acidity  -778 


A photograpnic  presentation  of  the  Sediment  discs,  showing 
the  amomit  of  dirt,  in  milligrams,  in  a pint  of  the  milk,  together 
with  its  acidity.  Figures  in  left  upper  corner  represent  the 
number  of  the  sample , while  those  in  right  upper  corner  represent 
the  number  of  the  patron. 


1 


[/ 


( 


I 

I 


i 


I 


:)'S  ^ 


I 


38 


PLATE  II  Samples  42-66. 


the  amount  of  dirt, in  milligrams,  in  a pint  of  the  milk,  together 


with  its  acidity.  Figures  in  left  upper  corner  represent  the 
number  of  the  sample,  v/hile  those  in  right  upper  corner  represent 
the  number  of  the  patron. 


PLATE  III.  Samples  6V-91. 


39 


6 0 fln^s.  ■ 

Acid/ty-./68 


69 


sm^s 
Acidity -./73 


70  2Z  7t  7 


SOmii. 

Acidity  -.211 


SOM^s. 
Acidity-  /63 


40/vris 
Acidity  —.158 


35 


S.OMfs. 

Acidity— ./57 


34 


Acidity  —754 


ZCMfs 
Acidity  — .782 


3.5  'i  20.o77i^s. 

Acidity  - 742  Acidity-  .752 
28 


32  76 


ijj. 

Acidity-772 


/SONIqs 

Acidity  —.747 


6.0A/lgs 
Acidity  -.762 


8! 


24 


ZSM^s 
Acidity-.782 


82 


29 


Allg: 

Acidity— .763 


88 


40fYi<ji. 

Acidity -.786 


PB. 


40A4js 

Acidity-  782 


EXT 


40AY\^s. 
Acidity  -.797 


39 


PB 


■Ik.  V 


4 0Ml^s 
Acidity  — 777 


86 


407ings. 
Acidity —.77/ 


v& 


i.SAA^s. 
Acidity  —.774 


90 


EXP  \ 9/ 


EXP 


■40/\Ags  40A7\gs. 

Acidity  -.765  .Acidity  — .795 


A photographic  presentation  of  the  Sediment  discs,  shov/ing 
the  amount  of  dirt,  in  milligrams,  in  a pint  of  the  milk,  together 
v/ith  its  acidity.  Eigures  in  left  upper  corner  represent  the 
number  of  the  sample,  while  those  in  right  upper  corner  represent 
the  number  of  the  patron. 


40 


PLATE  lY.  Samples  92-116. 


A pho-fco graphic  presentation  of  the  Sediment  discs,  shov/ing 
the  amonnt  of  dirt,  in  milligrar.is , in  a pint  of  the  milk,  together 
v;ith  its  acidity.  Pigures  in  left  upper  corner  represent  the 
number  of  the  sample,  while  those  in  right  upper  corner  represent 
the  number  of  the  patron. 


41 

Y.  DISCU3SI01T  OF  DATA. 

In  presenting  these  data,  the  authors  v/ish  to  emphasize  the 
fact  that  this  investigation  v^as  not  conducted  v/ith  the  aim  of 
determining  the  accuracy  of  the  foregoing  methods  in  a determina- 
tion of  the  germ,  content  of  a sample  of  milk.  It  v;as  realized 
that  each  method  has  its  faults  and  that  none  of  them  are  absolute! 
ly  accurate  and  it  v/as  the  aimi  to  compare  the  different  methods  in 
a system  of  grading  milk  under  conditions  as  found  in  this  locality 

Upon  interviewing  several  milk  dealers  in  this  locality  the 
authors  came  to  the  conclusion  that  raw  milk  with  a germ  content 
of  less  than  500,000  per  cc.  ?/hen  received,  was  considered  of  good 
quality.  These  dealers  expressed  the  opinion  that  if  they  could 
keep  the  germ  content  of  their  supply  belov/  500,000  per  cc.  they 
would  be  highly  satisfied  and  that  milk  with  a germ  content  of 
over  1,000,000  per  cc.  v/as  very  imde.sirable . 

The  results  obtained  "by  the  Standard  Plate  method  were  used 
as  a basis  of  comparison  and  the  results  of  the  other  methods  were 
compared  v/ith  these  results.  Upon  the  recormnendation  of  several 
prominent  milk  dealers  of  this  locality,  the  samples  were  divided 
into  three  classes,  namely: 

Class  "A".  Those  having  counts  of  less  than  500,000  per  cc. 
according  to  the  Standard  Plate  method. 

Class  "B".  Those  having  counts  of  500,000  to  1,000,000  per  cc . 
according  to  the  Standard  Plate  method. 

Class  ”0".  Those  having  counts  of  over  1,000,000  per  cc. 
according  to  the  Standard  Plate  m.ethod. 

From  the  results  as  indicated  in  the  recorded  data  it  would 
seem  that  there  is  a highly  comparable  relation  between  the  result! 


t ' *-p 


If.- 


V 

» 


Is. 


42  1 

obtained  by  the  Standard  Plate  method  and  those  of  the  Prost 
"Little”  Plate  method.  Phis  is  pointed  out  very  definitely  in  a 
study  of  Table  II,  out  of  the  85  samples  falling  into  class  "A" 
only  three  samples  having  a higher  count  than  the  maximum  of 
500,000  per  cc.  were  found  by  the  frost  method.  This  fact  is  fur- 
ther emphasized  by  Table  Z2III  and  Chart  I.  In  milh  of  a very 
low  germ  content  the  count  of  these  uv/o  methods  cheched  very  close 
ly  but  as  the  maximum  of  500,000  v;as  approached  the  percentage 
variation  increased.  Of  the  85  samples  recorded,  in  this  Table, 
of  the  Plate  counts  v;ere  higher  than  the  counts  obtained  by  the 
frost  method  and  44  of  the  frost  counts  were  higher  than  the  Plate 
counts.  In  this  respect  these  data  correlate  with  the  findings  of 
Sirmons^ who  recorded  that  the  frost  plates  run  2d)o  higher  than  the 
Plate  counts. 

Prom  Tables  III  and  IV  it  \70uld  seem  that  the  Breed  method  is 
not  very  reliable  for  high  grade  milk{less  than  500,000  per  cc.). 
ITo  coimt  was  obtainable  by  this  method  on  26  samples  in  Class  "A". 
There  is  a closer  correlation  where  the  clusters  were  counted  than 
v;here  the  individual  organisms  xiexe  counted'^.  Where  individuals 
were  recorded,  16  exceeded  the  maximum  of  500,000  per  cc.,  while 
only  three  exceeded  the  maximum  of  500,000  per  cc.  where  clusters 
\iexe  recorded.  This  is  undoubtedly  due  to  the  fact  that  the  col- 
onies as  counted  on  the  agsn  plates  were  produced  by  clusters  of 

G 

bacteria  as  well  as  by  single  organisms. 

Ov/ing  to  the  sm^all  number  of  samples  of  highly  contaminated 
milk  found  in  this  investigation  no  comparable  conclusions  can  be 
dra''vn  as  to  the  correlation  between  the  results  obtained  by  the 
Plate  method  and  the  microscopic  methods,  of  Breed  and  frost. 


I; 


/ 


i 


X . 


; r,  \ <■■  v:*'4  ■ ^ *’ 


> a 


V' 

: 'V.. 


■1  f-:Tai  ■oBJP', 


V 'i -jj-i  ?4^!’ 


*f  > 


.4  • f 

* 1 - 

I 

.:.  :rr‘ 
?»♦ 


1)  f • "v " ' ..’iMH 

' IIP 

,i.  y -C  ■» 


.'  ■■  J’"  j ,i  i ' ^ ^■  ' l»  ^ . 

•.  .5  , ;%  ■ ' ?■  AmO  .<J5;.^ 


<f  u ^4 \ -. ' ' ’■  ?»i r'l'i . ; ■ > i fy ' 'irtr^ 


.. .... # ‘■•i  ^ 

4 , - ■ ' 

.:’  'cf , ,j ■., ' • i : -.  i,  > .i;.- ' :■;  -i ''  V ' *Jt£i 


) ' 


' <1  1-. 


,'"i„  ■*‘^- 


• ' ...  ■ :v-‘ 

” l'|..  /'  •,.  >’S*'i 

■'•  ■ ' „)f  --’n  ■ ■ '.  . '■  ■■'■  ' 

J . 4'A-/.  .▲  ' .1  . 


^ 43 

While  these  comparisons  \:ere  made  according  to  the  classiiic- , 
ation  made  on  page  35,  attention  is  called  to  the  fact  that  the 
methods  are  highly  reliable  in  grading  milk  having  a germ  content  , 
of  less  than  100,000  per  cc..  59  samples  of  this  investigation  had  | 
a Plate  count  of  under  100,000  per'cc.;  of  these  59,  the  Prost 
method  placed  51  in  a class  of  under  100,000  per  cc.  v/hile  Breed 
(cluster)  placed  56  in  this  class,  hut  on  24  of  these  no  count  was 
obtainable  by  the  latter  method;  therefore,  it  was  not  considered 
quite  as  reliable  as  Prost.  Prom  this  it  may  be  said  that  even  in 
very  high  grade  milk  any  of  the  three  methods  is  quite  reliable, 
the  Plate  and  Prost  methods  being  more  so  than  the  Breed. 

fables  YIII,  IX  and  X,  XIV,XVand  XVI  seem  to  indicate  that 
the  results  obtained  by  the  Breed  method  correlate  raore  closely 
with  the  Plate  counts  than  do  those  obtained  by  the  Prost  method. 

Prom  a careful  study  of  fables  V,  XI  and  XVII  it  may  be  con- 
cluded that  a short  deduction  is  of  great  significance,  in  that 
almost  invariably  a short  Reduction  indicates  a high  count,  while 
on  the  other  hand  a high  count  does  not  necessarily  mean  a short 
Reduction.  Samples  101  and  114  in  fable  V had  a short  Reduction 
test,  v/hile  the  bacterial  count  was  comparatively  lov/.  In  fable 
XVII,  samples  37  and  117  had  a high  count  and  a long  Reduction  tes1  , 
which  would  indicate  that  a long  Reduction  test  does  not  have  as 
much  significance  as  does  a short  one.  these  fa,bles  lead  the  au- 
thors to  think  that  it  is  the  kinds  of  organisms  rather  than  the 
number  of  organisms  that  influence  the  Reduction  time;  however 
there  is  hardly  enough  data  to  draw  definite  conclusions. 

fhe  data  on  fables  VI,  XII  and  XVIII  indicate  that  there  is 
no  definite  correlation  between  the  acidity  of  the  milk  and  its 

nerm  content ■ ..  ■ - - 


A • 


t 

1) 


jl 


't 

I 

I 

i 


( 

( 


FT- 


t 


!l 

I 

m' 

M 


<• 


P ' 

,•■  f ft' -4<f  ft’-'am^e 

''  'I  * t 


44 

Tables  YII , XIII  and  XIX  indicate  no  correlation  between  the 


germ  content  of  the  milh  and  the  amount  of  insoluble  sediment  it 

contains,  in  which  respect  these  data  correlate  v/ith  the  findings 

8 

Harding  and  Prucha. 


■? 


! 

! 

* 

I! 


I; 

r 


n 


\ 


I. 


I 


.•1, 


1 


T, 


t 


I 


r 


'>1 


45 


VI.  smiMAP.Y  AlID  COl'IGLUSIOlTS. 

It  was  found  in  this  investi^ntion  that  any  of  the  three  meth- 
ods of  hacterial  analysis  of  milh,  namely:  Standard  Plate  method,  | 
ij’rost  "Little”  Plate  method,  and  Breed  method  may  he  successfully 
used  as  a basis  for  grading  market  milk,  fhe  adaptability  of  each 
method  depends  upon  other  factors  than  its  accuracy. 

The  i'rost  method  is  more  reliable  than  the  Breed  method  in 
grading  milk  of  low  germ  content,  but  not  as  reliable  for  more 
highly  contaminated  m.ilk,  unless  dilutions  are  ma,de  for  the  ±^rost 
plates . 

iThere  the  Breed  method  is  used  as  a basis  of  grading  milk, 
the  cluster  counts  should  be  averaged  for  the  final  count  rather 
than  the  individual  counts  if  the  Standard  Plate  method  is  accepted 
as  a basis  and  a close  correlation  is  desired. 

The  authors  are  of  the  opinion  that  the  variations  between  the 
Methylene -blue  Keduction  tests  and  the  Plate  counts  are  too  great 
to  warrant  their  use  as  a basis  of  grading  milk,  but  that  Methylene  - 
blue  Reduction  tests  have  value  as  an  indiction  of  the  keeping  quad  - 
ity  of  railk. 

Sediment  tests  have  no  relation  to  the  germ  content  of  a sam- 
ple of  milk  but  it  is  the  opinion  of  the  authors  that  they  are  an 
indication  as  to  the  sanitary  conditions  under  which  the  milk  was 
produced  and,  as  such,  are  of  value  in  a system  of  grading  milk, 
and  majr  be  successfiuLly  used  as  an  incentive  for  the  production  of 
cleaner  milk. 

There  is  no  correlation  between  the  acidity  and  the  germ  con- 
tent of  a sample  of  milk,  but  it  is  thought  that  some  light  is 

thrown  upon  the  sanitcry  conditions  of  its  production  anid  subse- 
Quent  handllnr?  and  that  it  is  an  index  as  to  its  koeoinr:  quality. 


